Conventional polyethylene terephthalate ("PET") resins generally have poor melt strength. Hence, molten PET tends to quickly collapse when foamed. Conventionally foamed PET can also generally have poor mechanical properties, due to broad differences in cells sizes, cell wall thicknesses and the like. Furthermore, conventional chlorinated fluorocarbon foaming agents are problematic, since they are generally deemed harmful to the environment. New foaming agents have been developed, but can be problematic for a variety of reasons.
Industrial and/or post-consumer polyester recycled resins are generally in more than abundant supply and such "waste" polyester is often landfilled, since a sufficiently large market for recylced polyester plastics has not been realized. This is problematic, since landfills are expensive and finite in their capacity to receive refuse. Furthermore, the melt strength and viscosity of post consumer and industrial recycle polyester resins are generally too low to produce adequate foamed structures with practical density reductions using conventional foam technology.
The present invention is directed to a new, economical use of industrial or post-consumer polyester waste and to new, economical and useful foams which comprise recycled polyester.